The dividing line between the two Koreas, whether the 38th parallel or military demarcation line, has been with us since 1945. The original division of Korea, considered a temporary military expediency to denote where Soviet and American forces should accept the surrender of Japanese troops, was portentous; the line never disappeared 67 years later, even after reshaped by battle after the Korean War. This paper contends that the 1945 division of Korea reflected by the United States little aforethought about Korea’s strategic position and low regard for the Korean people’s ability to self-govern as an independent nation. America’s designation of occupation zones in Korea was poorly handled, with enormous consequences for the Korean people. It arguably was part of a legacy of mismanaging a series of “big decisions” affecting Korea that continue to this day. The lesson of history for the U.S. is to be better informed and prepared to fulfill its responsibility toward the Korean peninsula; as a signatory to the Armistice it must be a participant in a permanent peace agreement. The creation of a governmental U.S. institute for Korean unification affairs as a counterpart to the organizations that exist in South Korea and North Korea is recommended preparatory step.